Hypoxia is a component of perinatal hypoxia/ischemia (H/I) and asphyxia accidents that is an increasingly common cause of brain injury and subsequent neurological deficits during gestation/delivery and in young children suffering accidental asphyxia. The routine treatment of hypoxia with 100% normobaric oxygen -hyperoxia, may exacerbate injury. Our long-term goal is to characterize the consequences of cell death due to hypoxia/hyperoxia that place brain recovery and neural development at risk, in order to develop rational therapeutic interventions. All hypoxic insults to the brain share early energy failure and acute oxidative stress that trigger delayed cell death. Our hypothesis is that recovery from hypoxia/hyperoxia is in part via stimulation of NF-kappaB-regulated Bcl-xL expression; thus, neurons surviving hypoxia have higher levels of Bcl-xL. A corollary is that manipulation of Bcl-x promoter-specific NF-kappaB activity can enhances recovery. The stress responses of P7 rats that are exposed to hypoxia and hypoxia hypoxia/hyperoxia in gas-controlled chambers will be assessed in terms of changes in terms of NF-kappaB activity and Bcl-x expression as measured by quantitative electrophoretic migration shift assays (EMSA), western blot analyses, Microaffinity isolation/western immunoblot assays (MI/WlA), MRNA ribonuclease protection assay (RPA), and immunocytochemistry. The binding of hypoxia/hyperoxia-induced NF-kB proteins to the two Bcl-x promoter specific NF-kB binding consensus sequences will be quantitatively measured using above-mentioned techniques and DNA footprinting analyses. The regulation of Bcl-x expression by NF-kB (p50, p52, p65, c-Rel, and RelB) and IkB (IkBa and Bcl-3) proteins will be assessed by promoter analyses using mutant promoter-reporter expression in hippocampal primary cell cultures. Interventions in NF-kB activity via use of inhibitors, "decoys", and gene transfer approaches will be assessed in P7 brain using above-mentioned techniques as well as DNA microarray analyses including the use of bioinformatics analyses. Understanding Bcl-x transcriptional regulation after hypoxia and hypoxia/hyperoxia wilt allow design of rational interventions in perinatal asphyxia and hypoxia.